1. Field of the Invention
The subject invention generally relates to mitigation of a thermal runaway event and more particularly relates to the mitigation of propagation of a thermal runaway event in a multi-cell battery pack for use in an electric vehicle.
2. Description of Related Art
It is well known in the prior art to use all electric vehicles to provide transportation for occupants. Many of these prior art electric vehicles carry several thousand pounds of nickel metal hydride batteries to achieve a long range electric vehicle for everyday use by consumers. Furthermore, many of these prior art electric vehicles need to be physically large and heavy to accommodate all of these batteries, such that these vehicles are not capable of achieving necessary acceleration, handling, performance and the extended range needed for an electric vehicle to become a feasible option for public purchase and use. Many prior art electric vehicles that were of normal size and not overly heavy, would have a very small range, thus reducing the feasibility for large mass selling of such vehicles to the consuming public. Furthermore, many of these prior art electrical vehicles which use such batteries had problems with protecting the occupants in the vehicle from the high voltage components and high temperatures that emanated from such high voltage components and still provide a vehicle that moves at a acceptable speeds compared to that of a gasoline or diesel internal combustion engine equipped vehicle. Some of these prior art electrical vehicles have had problems with their batteries overheating, thus reducing the range of the electrical vehicle and the durability and overall life of the batteries or cells that are part of the battery pack systems within the prior art electric vehicle.
Generally, batteries or cells are arranged within many prior art vehicles that operate with high power output which increases the temperature and hence may reduce longevity of the prior art batteries. The use of the heavy and high voltage battery systems in prior art electrical vehicles requires a lot of maintenance to keep the batteries operating due to the high temperatures at which the battery pack systems tend to operate. Some of these prior art systems try to increase the longevity of the batteries by using air cooled systems that blow cooled air over the batteries to try to remove heat from the battery compartment and batteries in these prior art electric vehicles. However, many of these prior art heat reduction systems for the batteries are not very efficient and do not provide an efficient system for balancing and removing heat or adding heat to the batteries. Hence, many prior art systems may suffer from overheating or overcooling, thus reducing the durability and longevity of the batteries and hence the range of the electric vehicle. Furthermore, in some of these prior art vehicles if one battery cell got too hot it would propagate and lead to a thermal runaway of the entire battery pack and all of the batteries therein, thus greatly reducing the longevity and the ability of the cells to hold a charge or completely destroying the battery pack. This would result in a full replacement of the battery pack and down time for the electric vehicle thus effecting the overall feasibility for selling such electric vehicles to the consuming public.
Therefore, there is a need in the art for an improved system to mitigate propagation of a thermal runaway event for use in a battery pack of an electric vehicle. There also is a need in the art for a methodology and system that will maximize the longevity and performance of the battery pack by reducing the impact of an overheating cell within a battery pack. There also is a need in the art for a system that will mitigate any thermal runaway with a variety of systems thus increasing the chances that an overheating cell will not affect any adjacent cells and/or the entire battery pack or energy storage system. There also is a need in the art for a system of mitigating thermal runaway that will actively and passively cool the cells in an energy storage system. There also is a need in the art for a mitigation system to prevent thermal runaway in a multi-cell battery pack that is capable of sensing a plurality of overheating situations and activating necessary controls to thwart the overheating and minimize the ability of a thermal runaway propagation event to take place within the battery pack.